Environmental and Flooding

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The board of Occupy Madison, Inc. has submitted the following answers to community questions. The answers are, however, a work in progress and may change as we get additional community feedback and as we find out more information. Additionally, the village will be a cooperative and the rules are primarily developed by the members of that cooperative living on the site and will be adjusted over time. If you have additional questions, please submit them below.

How will you deal with the flooding in the area?
Our houses are on wheels and are about a foot and a half or more off the ground. We will move them on the site away from areas that flood. Additionally we are talking with the city engineering department about rain gardens and other features to help mitigate the flooding, including participating in the terrace rain garden program if we have the opportunity. If necessary, we will consider grading the site to further address the situation. Additionally, we plan to create additional landscaping areas that would be built on top of the current blacktop raising the area around the houses further.

UPDATES FROM CITY ENGINEERING:
From Greg Fries:

I have attached a copy of the storm sewer records for the area. The storm sewer was upgraded in 1997 and is about as big as we can physically fit under the ground at this point. The difficulty lies in that this area sits only about 2 feet above the flood stage for Lake Monona / Yahara River where this area is drained and the pipe that drains this area is partially to fully underwater at times of the year. I am not convinced there is much we can do about the flooding problem here except make sure any redevelopment is set sufficiently high so that it does not flood.

What will you do with the compost from the composting toilets?
The composting toilet we have is made by Nature’s Head. A couple can use it on weekends for an entire summer without needing to empty the solids tank. There will be no storage or use of human waste compost on the site. The composting toilet separates the liquids from the solids. The liquids can be disposed of in a toilet. The solids will be disposed of like any RV or we will have a porta-potty company come and dispose of the contents quarterly or as necessary. We anticipate that the composting toilets will get minimal use as there will be two men’s and two women’s restrooms available for use in our building. Restrooms will be monitored by the Department of Public Health as they regulate campgrounds. The toilet is US Coast Guard approved.

This is a brownfield/old gas station, what are they existing conditions and what precautions are being taken for the people living there?
The biggest concern is petroleum contamination and leaking underground tanks. This tank was closed in 2000. (2000 tank closure letter) There were 4 tanks total:

We will have to contact DNR before constructing a well, which we would never do and any remaining contaminated soil must be properly handled if disturbed. (i.e. any soil removed must be properly disposed of.) Here is more information about our continuing obligations. Here is the City map of Brownfield Assessment for the North Corridor.

UPDATE FROM CITY ENGINEERING:
From Sally Swenson:

Unless land will be dedicated to the City as part of your project, we would not require additional Phase I or Phase II investigations.

However, according to records available from the DNR, there is existing contamination on the site from former petroleum tanks. Benzene is of particular concern at this site. I have not reviewed the entire file, but based on the closure letter submitted to the Department of Commerce, then transferred to DNR (attached)

it appears that a soil vapor extraction unit was operating between 1991 and 1999 to mitigate the elevated levels of volatile organic compounds. The site was closed in 2000, at which time, I’m assuming the soil vapor extraction unit was removed. At the time of closure, elevated levels of volatile organic compounds still existed at this site, which is why soil capping was required. DNR guidance would be needed to determine appropriate steps for development. Soil capping may still be necessary, or additional sampling may determine that the contamination has since degraded to concentrations that no longer require capping. If the future development requires excavation near the former tank locations, contaminated soil will most likely be disturbed. This soil will need to be managed in accordance with current contamination levels, i.e. landfilled or treated as a solid waste.

Although not required by the City, I believe it would be prudent to have an environmental professional review the DNR file to determine if a Phase I has been completed for the site. If not, a Phase I may be a good idea as a precautionary measure. The existing contamination was created by a former gas station, but whether or not this site has always been a gas station, or whether or not the tanks were always sited in that location, is not clear from the documentation I have. The results of the Phase I would determine if a Phase II investigation would be necessary.

The WI DNR Bureau for Remediation and Redevelopment Tracking System lists Wendy Weihemuller as the contact for this file. I’m also attaching a link to the BRRTS online file for this site.

http://dnr.wi.gov/botw/GetActivityDetail.do?detailSeqNo=20253&siteId=0313000061

I hope this information helps. If you have any questions, please feel free to contact me.

How can you have gardens if the soil is contaminated?
Preliminary work done on neighboring property reveals that in order to mitigate soil issues we would have to remove two feet of soil and put down a barrier and replace the soil with new dirt. Experts who did the work tell us that there is essentially no greater contamination in the soil than there is in most of the dirt on the Isthmus. Most likely we would create gardens above ground to avoid soil contamination as well as deal with flooding issues.